1. Field of the Invention
The present invention relates to a system for generating control data for outputting predetermined control data corresponding to an operating position of a manually operable control means, such as an operating lever.
2. Description of the Background Art
FIG. 1 shows a conventional device for outputting a predetermined control signal in response to manual operation of a manually operable control means, such as a control lever. The device 100 shown in FIG. 1 comprises an operating lever 102 with one end rotatably fitted to a pivot 101 and a variable resistor 104 which has its electrical resistance variable as an operating shaft 103 rotates. The operating lever 102 is fitted with an arm 106 having gear teeth 105 on its circular arc centering around the pivot 101. Moreover, the variable resistor 104 is equipped with a small gear shown in engagement with the gear teeth 105 on the arm 106. A pair of stopper pins 108 are disposed at two points on the plane of pivotal movement of the operating lever 102 around the pivot 101. The orientations of the stopper pins 108 are so selected that the operating lever 102 contacts with one of the stopper pins 108 at a predetermined angular position in either of the pivoting directions. Therefore, the stopper pins 108 defines an angular range in which the operating lever 102 can be pivotally shifted.
As shown in FIG. 2, the variable resistor 104 has one end connected via a first regulating variable resistor 109 to a power source +V. The other end of the variable resistor 104 is connected to the ground via a second regulating variable resistor 110. The output terminal of the variable resistor 104 is connected to a control signal output terminal 111 and also connected to the aforementioned grounded end via a third regulating variable resistor 112.
In the conventional device set forth above, when the operator shifts a handle 113 fixed to the tip end of the operating lever 102 for causing pivotal movement of the operating lever, the operating shaft 103 of the variable resistor 104 rotates. Thus, the output corresponding to the operating position of the operating lever 102 at the control signal output terminal 111 can be obtained.
The foregoing conventional device encounters various defects or drawbacks. For example, in order to obtain the predetermined output corresponding to the operating position of the operating lever, the variable resistors 109, 110 and 112 are to be precisely adjusted so as to compensate for fluctuation in the characteristics of the variable resistor 104 and for error in installation of the operating lever 102. Even by precise adjustment of the variable resistors 109, 110 and 112, it is still difficult to provide satisfactorily high precision to output the predetermined value corresponding to the angular position of the operating lever. Furthermore, because of insufficient precision in the co-relation between the angular position of the operating lever and the output, with the conventional device it is difficult to set a plurality of angular positions at which mutually different outputs are to be obtained.